I'm using FreeBSD 8.0 and I've setup a jail, pgsql, to act as a database server. After installing, I've tried to run initdb but get the following error:

$ /usr/local/pgsql/bin/initdb -D /usr/home/pgsql
cannot create /dev/null: Permission denied
fgets failure: No such file or directory
The program "postgres" is needed by initdb but was not found in the
same directory as "/usr/local/pgsql/bin/initdb".
Check your installation.